"Alexander Technique", as described in Wikipedia, seems related to the things I've described here (though I haven't tried it myself).

If your urge to over-clock has no environmental cause or rational reason, maybe you have akathisia. See a doctor.

Last updated: 19 June 200427 May 2004

[Note: This theory is consistent with behaviours i have observed in myself and other people, but it has not been systematically tested.]

Your body can run fast or slow. It's as if you have some kind of internal clock
that runs at a variable rate. (Actually there are several internal "clocks",
but they're coordinated by the sympathetic nervous system and react in
parallel.)

You can be over-clocked. Your heart beats faster, you breathe faster, your brain
thinks faster. In this state you can react swiftly to events, thus successfully
avoiding dangers or exploiting opportunities. This isn't sustainable over
extended periods. Reserves are used up, muscles become sore, the mind
eventually becomes exhausted and goes blank. If you over-clock for a long
enough time, parts of your body start damaging themselves, you become more
suceptible to disease, everything becomes painful. You get stress.

You can be under-clocked. This allows your body to relax and recover. It
can replenish reserves of energy and repair damage. However while under-clocked
you are not able to deal with unexpected events.

Somewhere between these extremes is a break-even point, a clock rate at which
your body can cruise all day, neither burning reserves nor restoring them.
This is the state in which you can get the most done, and it is the state in
which you are happiest.

A change in speed affects many organs, it requires secretions and chemical
changes. You can't change speed instantly.
Therefore, at any given time your
clock must be ticking fast enough to deal with any event that might occur in
the near future.

Stress is not additive. Your level of stress is determined by how much you
over-clock, and your clock rate is determined solely by the possibile
event that would require the most speed to deal with.
Therefore:

A single sufficiently taxing random source of stress, even if it is very
unlikely to occur at any given moment, can burn you out.

You can take on a large number of moderately taxing things (things at the
break-even clock rate) without burning out. They won't add to your level of
stress, because stress is not additive. You may be able to do much more than
you are doing currently.

event occurs event dealt with
| |
|------------------->-------------->|
decide what to do do something

For some events, you have a limited time to react before something bad happens
or some opportunity is wasted. By over-clocking, you can reduce the time it
takes to think, and you can act faster, thus reducing the total time it takes
for you to react.

If an event requires no response, it may still take some time to realize
that, distracting you from other tasks. Over-clocking may be an attempt to
reduce the amount of time you are distracted (it won't work well though, when
you are going fast you tend to be more susceptible to distraction).

Even if an event occurs rarely, if it requires over-clocking you must
over-clock all the time. If you were to increase your clock rate only
when the event occurred, you would not be able to react fast enough, adjusting
your clock rate takes time.

Examples of things you might over-clock to try to deal with:
an annoying person who rings you at random times,
your boss walking in on you unexpectedly,
talking to other people if you have poor social skills,
an elevator button that always shocks you (if you flinch),
being in a class with a teacher who asks random people questions,
loud noises (if you flinch),
a phobia you must try to overcome at inconvenient times,
a problem (if you feel compelled to think about it when it pops into your head),
a distressing memory (if you are in the habit of doing something else to distract yourself from it),
an assignment with a looming deadline,
a dripping tap (if you let it annoy you),
chores that are preventing you from doing something else,
dogs that bark at you unexpectedly.

When your body is over-clocked, you have the option of moving fast and making
snap decisions. It's often easier to move fast than to move slowly. If you
habitually move fast when your body is over-clocked, your body will learn to
over-clock all the time so you can always move that fast. If you move slowly while over-clocked, your body can learn to slow down.

Note that simply sitting or laying still if you become over-clocked will not help. Your body will learn an appropriate speed of movement only if you are actually moving, if you are not moving it will learn nothing. Indeed animals when frightened will freeze until there is a good oportunity to escape, then bolt off extremely rapidly -- simply freezing is not inconsistent with being over-clocked.

A cat fight occurs when two people try to adopt the cat role
in a relationship (see Cats and Dogs).
One strategy in a cat fight is to try to always speak first when you run
into the other person. If the other person tries to do the same, you will both
be trying to be faster than the other, so in any situation where you might run
into that person you will have to have a fast clock rate.

A more laid back way to win a cat fight is to not respond to the other person
immediately. When they talk to you, allow enough of a pause that it does not
seem as though you are responding, and frame what you say in a way that would
also make sense if they had not spoken.

[Note: this may really really piss off the other person. Better not to get
into a cat fight in the first place, or to talk it through.]

In general, a group of people will unconsciously try to match the speed of the
fastest person in the group.

The sensation of successful slowing down is always one of letting go, of loosening the reins, of less effort. It is not a matter of opposing or restraining a force. Don't slam on the breaks, release the accelerator.

When slowing physically, you shouldn't pull back, tightening muscles to oppose your momentum or the force of other muscles. Instead, let your motion play out with no further input of energy. If you are walking or running, don't lean back and push against the ground to stop. Instead let your forward momentum play out and coast gradually to a stop.

When slowing mentally, don't forcefully dismiss thoughts from your mind. Instead let them play out without giving them any extra energy. Take a back seat, as if watching a play.

Slowing down can be a somewhat scary thing to do, and it has a distinct and peculiar sensation, as if allowing yourself to fall into the future.

Avoid situations that you over-clock in.
(a dangerous approach, if taken too far you will have no life)

Drugs. Propranolol will slow your body, but not your mind.
Clonidine will slow both your body and mind. Anti-depressants will do something or other, no one's quite sure what, possibly stop you from caring about
things quite so much. Benzodiazepines will slow you down, but make you stupid too.
(a dangerous approach, you can come to rely on drugs too heavily, and they can
cause some odd side-effects ... but worth looking at if other things aren't working)

Practice what you need to do to respond to an event, so that your thought
process when it occurs takes less steps and your actions require less focussed
attention. (this can also turn a boring job into a relaxing one)

Confront the thing that causes stress at a time of your own choosing, when you
can give it your full attention, and practice an unhurried response.

Find a slower way to respond to an event.
Do you absolutely have to react quickly?

If you have a habitual fast response to something, rehearse what
response you should have made immediately after each time the habit is triggered.
(trying to pre-empt a habit will require yet more speed. Not so good.
I find i unlearn bad habits fairly quickly using this rehearsing-afterwards
strategy, and it doesn't require any further stress)

The number one thing is not to try to reduce stress. Trying
harder just makes it worse, let yourself not stress about your
stress. Better to study how stress works, and gradually build up good
habits.